Short-process preparation process of nickel-based superalloy GH4648 forged bar billet

Abstract

The invention provides a short-process preparation process of a nickel-based superalloy GH4648 forged bar billet, which specifically comprises the following steps of: producing a cast ingot with uniform components by adopting vacuum induction melting (VIM) and vacuum consumable melting (VAR), and directly forging the cast ingot in a furnace to produce a qualified bar. VIM smelting is adopted, and the VIM electrode with uniform components and low gas content is obtained through high vacuum degree and strong stirring. In the VAR smelting process, a proper melting speed is selected, an arc-stabilized magnetic field is added, and finally the GH4648 alloy cast ingot which is compact in structure, good in component uniformity and low in impurity element and gas element content is obtained. The cast ingot is not subjected to homogenization heat treatment and can be directly forged into qualified bars with the specifications of phi 200mm, phi 250mm and phi 350mm, the flaw detection level is not lower than phi 0.8 mm-8dB, and the components and the performance meet the standard.

Description

Technical Field

[0001] The present invention relates to the technical field of high-temperature alloy smelting, in particular to a short-process preparation process for forging rods of nickel-based high-temperature alloy GH4648. Background Art

[0002] GH4648 alloy is a high-chromium (Cr)-content precipitation-hardening, deformable superalloy with excellent corrosion resistance, fatigue resistance, and creep performance. In the aviation sector, GH4648 alloy has become an indispensable material, widely used in engine combustion chamber components and other hot-end components. With the rapid development of China's aviation industry, the strategic value of superalloys has been fully explored. Both the military and civilian markets are placing higher demands on performance and quality, and contract delivery cycles have become a key criterion for evaluating each supplier's production capabilities.

[0003] Currently, GH4648 forging bar stock produced both domestically and internationally is generally made from GH4648 ingots produced using a dual process (vacuum induction melting + vacuum consumable melting). Due to the severe elemental segregation in the GH4648 ingots, homogenization treatment is required. This homogenization treatment involves numerous holding steps, long holding times, and extended cooling times within the homogenization furnace. It often takes more than a week, accounting for a quarter of the entire bar production cycle. Summary of the Invention

[0004] The object of the present invention is to provide a short-process preparation process for forging rods of nickel-based high-temperature alloy GH4648, so as to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above-mentioned object, the present invention provides the following technical solution: a short-process preparation process for forging rods of nickel-based high-temperature alloy GH4648, which specifically includes the following contents:

[0006] Step 1: Obtain GH4648 alloy VIM electrode by vacuum induction melting (VIM);

[0007] Step 2: Annealing the VIM electrode obtained in step 1;

[0008] Step 3: The VIM electrode obtained in step 2 is subjected to vacuum autoclave melting (VAR) to obtain a GH4648 alloy ingot.

[0009] Step 4: The GH4648 alloy ingot obtained after step 3 is continuously re-melted and forged to obtain a GH4648 alloy forging bar.

[0010] Preferably, the room temperature tensile strength of the prepared GH4648 alloy bar is 810MPa~820MPa, the room temperature tensile yield strength is 350MPa~380MPa, the room temperature tensile elongation is 50%~55%, the high temperature tensile strength at 800℃ is 520MPa~530MPa, the high temperature tensile elongation at 800℃ is 30%~45%, the high temperature cross-sectional shrinkage at 800℃ is 30%~40%, and the grain size is 4~5.

[0011] Preferably, in step 1, the chemical composition of the GH4648 alloy VIM electrode is as follows, by mass percentage: C: 0.040% to 0.10%, W: 4.30% to 4.70%, Mo: 2.30% to 2.60%, Cr: 33.0% to 35.0%, Nb: 0.60% to 0.90%, Ti: 0.60% to 0.90%, Al: 0.60% to 0.90%, B: 0.0030% to 0.0065%, Ce: 0.020% to 0.025%, Fe: 2.00% to 3.00%, and the rest is Ni, and the sum of the mass percentages of the above components is 100%.

[0012] Preferably, in step 2, the GH4648 alloy VIM electrode is placed in a natural gas furnace for heating treatment, with a heating rate of 30-100°C / h, a heating temperature of 600°C to 1000°C, and a holding time of 6h to 10h. After the holding is completed, the furnace is cooled to below 400°C and then taken out of the furnace for air cooling.

[0013] Preferably, in step 3, the self-consumable stable smelting stage adopts melting rate + droplet control, the melting rate is 3.0-5.0 kg / min, and the droplet is 3-121 / s.

[0014] Preferably, in step 3, an arc-stabilizing magnetic field is added, and the magnetic induction intensity is 15-70Gs.

[0015] Preferably, in step 4, the forging temperature of GH4648 during forging is 1130° C. to 1150° C., and 7-fire upsetting forging is adopted, with the deformation of each fire being 25% to 50%.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1) The GH4648 alloy ingot produced by the present invention has good composition uniformity and small radial range of elements such as Cr, Mo, W, Nb, Ti, and Al;

[0018] 2) The GH4648 alloy ingot produced by the present invention is directly forged without homogenization treatment. The resulting GH4648 forged rod has a room temperature tensile strength of 810MPa-820MPa, a room temperature tensile yield strength of 350MPa-380MPa, a room temperature tensile elongation of 50%-55%, a high temperature tensile strength of 520MPa-530MPa at 800°C, a high temperature tensile elongation of 30%-45%, and a high temperature reduction of 30%-40% at 800°C. The grain size is grade 4-5, and the flaw detection level is not less than Φ0.8mm-8dB. The composition meets the standard requirements.

[0019] 3) The GH4648 forging bar produced by the present invention has a shorter production process, less delivery pressure and lower cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a physical picture of GH4648 forging bar.

[0021] Figure 2 This is the high-magnification structure of the GH4648 forging rod in the embodiment.

[0022] Figure 3 This is the high-magnification structure of the GH4648 forging bar in the comparative example. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] See also Figure 1-Figure 3 The present invention provides a technical solution: a short-process preparation process for forging rods of nickel-based high-temperature alloy GH4648, which is specifically implemented according to the following steps:

[0025] Step 1: A GH4648 alloy VIM electrode is obtained by vacuum induction melting (VIM). The chemical composition of the electrode is as follows, by mass percentage: C: 0.040% to 0.10%, W: 4.30% to 4.70%, Mo: 2.30% to 2.60%, Cr: 33.0% to 35.0%, Nb: 0.60% to 0.90%, Ti: 0.60% to 0.90%, Al: 0.60% to 0.90%, B: 0.0030% to 0.0065%, Ce: 0.020% to 0.025%, Fe: 2.00% to 3.00%, and the remainder is Ni. The sum of the mass percentages of the above components is 100%.

[0026] Step 2: annealing the VIM electrode obtained in step 1, specifically: placing the GH4648 alloy VIM electrode in a natural gas furnace for heating treatment, with a heating rate of 30-100°C / h, a heating temperature of 600°C to 1000°C, and a holding time of 6h to 10h. After the holding period, the furnace is cooled to below 400°C, and then taken out of the furnace for air cooling;

[0027] Step 3: Vacuum consumable melting (VAR) is performed on the VIM electrode obtained in step 2. During the VAR stable melting stage, the melting rate and droplet control are adopted, with a melting rate of 3.0-5.0 kg / min and a droplet of 3-121 / s. A stabilizing arc magnetic field is added throughout the melting process, with a magnetic induction intensity of 15-70 Gs.

[0028] Step 4: The GH4648 alloy ingot obtained after step 3 is continuously remelted and forged. The forging temperature of GH4648 is 1130° C. to 1150° C., and 7-fire upsetting forging is adopted. The deformation of each fire is 25% to 50%.

[0029] Example

[0030] The present invention provides a short-process preparation process for a nickel-based high-temperature alloy GH4648 forging bar billet, which is specifically implemented according to the following steps:

[0031] Step 1: A GH4648 alloy VIM electrode is obtained by vacuum induction melting (VIM). The chemical composition, by mass percentage, is as follows: C: 0.070%, W: 4.40%, Mo: 2.50%, Cr: 34.0%, Nb: 0.75%, Ti: 0.75%, Al: 0.75%, B: 0.0050%, Ce: 0.020%, Fe: 2.80%, and the remainder is Ni. The sum of the mass percentages of the above components is 100%.

[0032] Step 2: annealing the VIM electrode obtained in step 1, specifically: placing the GH4648 alloy VIM electrode in a natural gas furnace for heating at a heating rate of 60°C / h, a heating temperature of 950°C, and a holding time of 10 hours. After the holding time is completed, the furnace is cooled to below 400°C, and then taken out of the furnace for air cooling;

[0033] Step 3: Vacuum consumable melting (VAR) is performed on the VIM electrode obtained in step 2. During the VAR stable melting stage, the melting rate and droplet control are adopted, with a melting rate of 3.0 kg / min and a droplet of 5 1 / s. A stabilizing arc magnetic field is added throughout the melting process, with a magnetic induction intensity of 30 Gs.

[0034] Step 4: The GH4648 alloy ingot obtained after step 3 is continuously remelted and forged. The forging temperature of GH4648 is 1150° C., and 7-fire upsetting forging is adopted. The deformation amount of each fire is 30%-40%.

[0035] The rod head was sliced, and samples were taken from the edge and core in the radial direction for composition testing. The results are shown in Table 1.

[0036] Table 1 Composition of GH4648 alloy billet

[0037]

[0038] The GH4648 alloy bar without homogenization treatment has good composition uniformity, and all test results meet the standards. The grain size is level 4 to 5, and the flaw detection level is not less than Φ0.8mm-8dB.

[0039] Comparative Example

[0040] The present invention provides a short-process preparation process for a nickel-based high-temperature alloy GH4648 forging bar billet, which is specifically implemented according to the following steps:

[0041] Step 1: A GH4648 alloy VIM electrode is obtained by vacuum induction melting (VIM). The chemical composition, by mass percentage, is as follows: C: 0.070%, W: 4.40%, Mo: 2.50%, Cr: 34.0%, Nb: 0.75%, Ti: 0.75%, Al: 0.75%, B: 0.0050%, Ce: 0.020%, Fe: 2.80%, and the remainder is Ni. The sum of the mass percentages of the above components is 100%.

[0042] Step 2: annealing the VIM electrode obtained in step 1, specifically: placing the GH4648 alloy VIM electrode in a natural gas furnace for heating at a heating rate of 60°C / h, a heating temperature of 950°C, and a holding time of 10 hours. After the holding time is completed, the furnace is cooled to below 400°C, and then taken out of the furnace for air cooling;

[0043] Step 3: Vacuum consumable melting (VAR) is performed on the VIM electrode obtained in step 2. During the consumable stable melting stage, the melting rate and droplet rate are controlled, with a melting rate of 3.0 kg / min and a droplet rate of 5 1 / s. No arc stabilizing magnetic field is added during the entire melting process.

[0044] Step 4: The GH4648 alloy ingot obtained after step 3 is continuously remelted and forged. The forging temperature of GH4648 is 1150° C., and 7-fire upsetting forging is adopted. The deformation amount of each fire is 30%-40%.

[0045] Table 2 Composition of GH4648 alloy billet

[0046]

[0047] The GH4648 alloy billets produced without homogenization treatment and without the use of ingots melted in a stable arc magnetic field have poor composition uniformity and bands can be observed under high magnification.

[0048] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A short-process preparation process for forging rods of nickel-based high-temperature alloy GH4648, characterized by: Specifically include the following: Step 1: Obtain GH4648 alloy VIM electrode by vacuum induction melting (VIM); Step 2: Annealing the VIM electrode obtained in step 1; Step 3: The VIM electrode obtained in step 2 is subjected to vacuum autoclave melting (VAR) to obtain a GH4648 alloy ingot. Step 4: The GH4648 alloy ingot obtained after step 3 is continuously re-melted and forged to obtain a GH4648 alloy forging bar.

2. The short-process preparation process for forging rods of nickel-based high-temperature alloy GH4648 according to claim 1, characterized in that: The room temperature tensile strength of the GH4648 alloy bar is 810MPa-820MPa, the room temperature tensile yield strength is 350MPa-380MPa, the room temperature tensile elongation is 50%-55%, the high temperature tensile strength at 800°C is 520MPa-530MPa, the high temperature tensile elongation at 800°C is 30%-45%, the high temperature cross-sectional shrinkage at 800°C is 30%-40%, and the grain size is grade 4-5.

3. The short-process preparation process for forging rods of nickel-based high-temperature alloy GH4648 according to claim 1, characterized in that: In step 1, the chemical composition of the GH4648 alloy VIM electrode is as follows, by mass percentage: C: 0.040% to 0.10%, W: 4.30% to 4.70%, Mo: 2.30% to 2.60%, Cr: 33.0% to 35.0%, Nb: 0.60% to 0.90%, Ti: 0.60% to 0.90%, Al: 0.60% to 0.90%, B: 0.0030% to 0.0065%, Ce: 0.020% to 0.025%, Fe: 2.00% to 3.00%, and the rest is Ni. The sum of the mass percentages of the above components is 100%.

4. The short-process preparation process for forging rods of nickel-based high-temperature alloy GH4648 according to claim 1, characterized in that: In step 2, the GH4648 alloy VIM electrode is placed in a natural gas furnace for heating treatment, with a heating rate of 30-100°C / h, a heating temperature of 600°C to 1000°C, and a holding time of 6h to 10h. After the holding is completed, the furnace is cooled to below 400°C and then taken out of the furnace for air cooling.

5. The short-process preparation process for forging rods of nickel-based high-temperature alloy GH4648 according to claim 1, characterized in that: In the step 3, the self-consumable stable smelting stage adopts melting rate + droplet control, the melting rate is 3.0-5.0 kg / min, and the droplet is 3-121 / s.

6. The short-process preparation process for forging rods of nickel-based high-temperature alloy GH4648 according to claim 1, characterized in that: In step 3, an arc stabilizing magnetic field is added, and the magnetic induction intensity is 15-70Gs.

7. The short-process preparation process for forging rods of nickel-based high-temperature alloy GH4648 according to claim 1, characterized in that: In the forging process of GH4648 in step 4, the forging temperature is 1130° C. to 1150° C., 7-fire upsetting forging is adopted, and the deformation amount of each fire is 25% to 50%.

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